Mounting devices to objects that are, or may be, exposed to unpredictable and varying force vectors caused by wind, rain, and other elements of weather present technical problems often difficult to solve. A long standing and unsolved challenge in the solar energy industry, for example, has been resolving how best to mount panels, modules and arrays of photovoltaic devices (collectively, “module” or “modules”) on surfaces not only securely and safely, but also quickly. The obverse problem also is significant to the industry, namely safely removing or reconfiguring a module that has been installed on a surface.
Solar energy radiation from the sun is capable of producing heat, causing chemical reactions, or generating electricity. The sun is an extremely powerful energy source, and solar radiation is by far the largest source of energy received by Earth, but its intensity at the Earth's surface is comparatively low. This is partly because Earth's atmosphere and its clouds absorb or scatter as much as 54 percent of all incoming sunlight. Solar energy, however, due to technological improvements in the manner of collecting the potential energy, has become increasingly attractive as an energy source: it is inexhaustible in supply, and non-polluting, both in stark contrast to fossil-fuel sources like coal, oil, and natural gas.
Sunlight reaching earth consists of approximately 50 percent visible light, 45 percent infrared radiation, and small amounts of ultraviolet light and other forms of electromagnetic radiation. Radiation is convertible either into thermal energy or directly into electricity by photovoltaic cells. In photovoltaic cells, a small electrical voltage is generated when light strikes the junction between a metal and a semiconductor or a junction between two different semiconductors. Although the voltage generated from a single photovoltaic cell typically is only a fraction of a volt, by connecting large numbers of cells together into panels, modules and arrays, significant electric power can be generated. To harness radiation for direct generation of electricity using cells collected into panels, modules and arrays, a number of apparatus and methods for using and installing the apparatus have been devised on which to mount modules on surfaces exposed to the radiation. The construction, installation, and use of such apparatus present a number of unsolved problems.
A wide variety of clamp assemblies, racks, frames and associated hardware have been proposed to mount modules on objects. Some solutions have proposed modifications of the shape, structure and size of components of a module to achieve more rapid and secure mounting. Other solutions have proposed altering the construct and design of hardware associated with installing racks, framing, and footings into a footing grid on which modules are mounted. As used in this document the term “footing grid” includes at least a network of keepers often, but not exclusively, L-shaped and formed with at least one hole in each extension of the “L.” The keepers are connectable to a surface and are formed and shaped to permit attachment of other hardware components such as rails and frames on which modules may be attached.
Prior approaches suggested for mounting a module on an object include significant limitations and problems. A serious challenge to providing a useful apparatus and method for mounting a module on a surface arises from the variety of sizes and shapes of the modules, as well as the varying number of modules that might be required in a given situation. Another challenge that earlier suggestions did not overcome is the variety of surfaces on which modules may or must be mounted, including roofs, tops and sides of poles, the ground, and other locations. Earlier solutions, therefore, required construction of custom built racks to fit each of the enumerable iterations of the sizes and shapes of modules.
Many earlier suggestions for mounting panels, modules and arrays of photovoltaic devices on surfaces are cumbersome, unsafe, and not easily assembled or reconfigured. In the industry associated with clamps for installation of photovoltaic modules, the term “top down” refers to attaching a module to a rail on a frame using a clamp that secures to the uppermost portion of the module. For example, in the case of a module to be mounted on a building, one or more rails first would be attached to a footing grid that earlier has been attached to the surface, in this instance the roof; thereafter, one or more modules would be attached to the rails. Hardware that secures the module to the rails is attached from the top, or front, of the module. The term “bottom up” refers to positioning a photovoltaic module by first attaching the module to the footing grid and to the roof or other surface. In bottom up mounting, hardware used to secure the module to the rail is attached from the bottom or back of the module. The uniqueness of each installation, an installer's preferences, and the particular module all will determine whether a top down or bottom up installation is used. The embodiments described in the present disclosure refer to the top-down configuration.
Another limitation of current approaches for mounting photovoltaic modules to a surface is the excessive number and variety of hardware parts and components that are required for each clamp assembly. Each module or combination of modules installed may present different shapes, sizes and configurations, thus requiring a unique combination of mounting hardware.
Yet another limitation of current approaches for mounting modules to a surface is the location where clamps for securing the modules to the rails may be placed. Several current approaches require the clamp to be placed in a specific location to secure to the rail and in turn secure the module to the clamp. There is a need for a clamp that may be placed anywhere along a rail to securely clamp a module to a rail.
Still another limitation of current approaches is that in addition to securely clamping modules to rails, there must be a means for efficiently providing an electrical ground route in the case of a fault. Modules contain electric current that flows between the modules and to a storage module. In the case of a fault during installation, there is a need for a ground route between the modules so that current is safely diverted to ground. Prior art configurations require a separate infrastructure to for grounding the modules that can malfunction or otherwise be rendered inoperable. There is a need for a clamp that provides integrated bonding between modules to provide a ground route without the need for additional infrastructure.
Another limitation of current approaches to clamping modules to supports such as rail systems, is the use of a bolt that serves as both a fastener and a slider. According the current approaches, a bolt is inserted into a slot in a rail and is oriented such that the head of the bolt is within the slot and a clamp is placed over at least a portion of the panel and the bolt so that the bolt extends through the clamp. Unpredictable and varying force vectors caused by wind, rain, and other elements of weather as well as errors in installation may cause these clamp assemblies to disengage from the support system, causing a module to come loose and interrupt the electrical current between the modules or potentially fall off the support system.
Still another unresolved problem arises from the varying shapes, sizes and configurations of modules. The arrangement of the modules on a surface such as a roof may not be dimensionally consistent with the location of rafters underneath the roof into which hardware must be inserted to hold the footing grid and rails. Clamps for securing varying sized modules to rails are currently available in various sizes. These sized clamps require an installer to carry multiple clamps of varying sizes and fit each clamp before to ensure a proper fit. Additionally, there may be some modules for which none of the clamp sizes securely clamp the module to the rail. This could lead to a loose connection or loss of connection to the rail.
Therefore, a previously unaddressed need exists in the industry for a new and useful clamp assembly for positioning a device such as a photovoltaic panel, modules and arrays of photovoltaic devices on a surface such as a roof, pole or other surface. Particularly, there is a significant need for a method and apparatus for mounting one or more photovoltaic modules safely, reliably, yet quickly on a surface; removing or reconfiguring the modules just as safely, reliably and quickly; and providing a clamp assembly that is adjustable and expandable to allow a variety of dimensions and configurations. Additionally, there is a need for a new and useful clamp that will secure a module to a support and resist loads in all three directions while providing integrated bonding between the modules.